Adjective : a dependable employee.    From Dictionary.com. 

The older "Queen's knights" must have naturally felt her devotion to him; his "undependableness" -- in consequence not merely of his fits of madness but of his chivalrously permissible but very inconvenient habit of disguising himself and taking the other side -- must have annoyed the whole Table.    From Wordnik.com.  [A History of the French Novel, Vol. 1 From the Beginning to 1800] Reference